Percentage Change Calculator
Calculate percentage change, increase or decrease between two values. With negative handling. Free.
How to use the % Change
Percentage change formula
% change = ((New − Old) ÷ |Old|) × 100. A positive result is an increase, negative is a decrease. From 100 → 150 = +50%. From 150 → 100 = −33.3% (not −50% — the base for comparison changes when you reverse direction).
Common confusions
If something doubles, it's a +100% increase, not 200%. If something halves, it's a −50% decrease. You can't have less than −100% (something can't decrease by more than itself). Going from 0 is undefined — you can't divide by zero, so % change from zero has no answer.
Frequently asked questions
How do I calculate percentage change?
Subtract the old value from the new value, divide by the old value and multiply by 100. For example, going from 50 to 60 is (60 - 50) / 50 x 100 = 20% increase.
Why is a 50% drop not reversed by a 50% rise?
Because the base changes. A 50% fall from 100 gives 50; a 50% rise from 50 gives only 75. To get back to 100 you need a 100% rise.
What if the old value is zero?
Percentage change from zero is undefined because you cannot divide by zero. The tool flags this case.